New 12v battery installation help

[Nicks]

Hi guys,

So I've decided to get a new AGM battery for my sailboat which will only be connected to my solar panel.

From this battery I will only run radio + USB charging ports and it wont be connected to my other battery as this is lead acid on just works as a starter.

I've been trying to figure out how to wire it all by myself, but I'm not really sure, hoping someone could help me out with the missing pieces.

If you check out the diagram in the attachment you can see my idea.

Now I am assuming this is correct, but there must be a better way of running the negative wire, other than all the way back to the battery. Is there a solution like using something like a fusebox for the negative wire?

And about the wiring, which wires do I use? is there something special for marine use? And how about wire-sizing for the different installations?

The positive wire going from the battery to the fusebox I guess must be bigger than the individual wires going from the fusebox?

Same for ground?

[socaldmax]

I have a few suggestions for you, and these are by no means comprehensive, I'm sure others will chime in with even more info for you.

1. Use marine grade (tinned) cable.
2. Use the correct size cable for the current, you can find charts online that will tell you what size cable to use for a particular current and distance.
3. Add a Negative bus bar near the fuse box, I'm a big fan of gold plated fuse boxes and bus bars due to their corrosion resistance, and they're usually about the same price or a tiny bit higher than the regular ones.
4. Run your solar output into your fuse box instead of having a fuse just hanging about somewhere in the line, that's what fuse boxes are for, to keep all of your fuses together.
5. Instead of fuses, I prefer circuit breakers. That way if one pops, you don't have to fumble around looking for the replacement fuses (one never has the right sized spares anyway.) Since something is now drawing more current than normal, you now have to find and fix the problem, then test, which could result in burning up all of your spare fuses if it takes a number of tries to get it nailed down. With CBs, you just reset it, if it pops again, you know you didn't fix the problem.

They sell a variety of resettable circuit breakers, one style fits into the regular ATO slots:


or if you really want to get fancy, you could go with the round aircraft style breakers that also act as switches:


They're top quality, sealed, and if you shop around, can be found fairly low priced. Notice how they're using these to isolate the batteries and alternators as well.

[smac999]

Bluesea 5025 for fuse block. Pos and neg.

[Terra Nova]

Originally Posted by Nicks

...Is there a solution like using something like a fusebox for the negative wire?

And about the wiring, which wires do I use? is there something special for marine use? And how about wire-sizing for the different installations?

The positive wire going from the battery to the fusebox I guess must be bigger than the individual wires going from the fusebox?

Same for ground?

A man's gotta know his limitations. Hire a pro.

[Nicks]

Originally Posted by smac999

Bluesea 5025 for fuse block. Pos and neg.

Thanks! That's exactly what I was looking for!

A man's gotta know his limitations. Hire a pro.

This is a an electrical system, not rocket science, just needed some help with a few things that I did not know (this is all new to me).

I don't want to hire someone for it, I want to learn how this stuff works.

[Nicks]

Originally Posted by socaldmax

I have a few suggestions for you, and these are by no means comprehensive, I'm sure others will chime in with even more info for you.

1. Use marine grade (tinned) cable.
2. Use the correct size cable for the current, you can find charts online that will tell you what size cable to use for a particular current and distance.
3. Add a Negative bus bar near the fuse box, I'm a big fan of gold plated fuse boxes and bus bars due to their corrosion resistance, and they're usually about the same price or a tiny bit higher than the regular ones.

This was great! Exactly what I needed to know. Found a great chart for finding cable sizes + fuses etc.

A Negative bus bar was exactly what I was looking for - I see the guy below you recommended a fusebox that seemed to have one of those integrated, so I'm going to use that to keep it all together.

Thanks again for your reply mate!

[wrwakefield]

Hi Nicks,

You are right to do this kind of work yourself- especially if you are going to be caring for the boat on an ongoing basis.

I've been doing so for decades on several different vessels over time, and still learn tricks and techniques from the quality books available.

In your case, if you don't already have a copy (and it doesn't sound like you do) I suspect you would benefit from consulting Nigel Caulder's Boat Owners Mechanical and Electrical Manual [among ay other worthy publications...]

Let me know if you disagree once you peruse a copy...

Have fun with your projects!

[exMaggieDrum]

Blue Sea and West Marine both have some very good basics articles about battery/circuit wiring with diagrams etc. Highly recommended and easier to read and understand than Calder's books (good but dense). Tin plated is pretty much as good as gold plated from what I have seen but it is all about the same price. Go with whichever you get first. Blue Sea has excellent gear. That's what I use for the most part. You can find cheaper but if you do make sure it is good quality.

[Nicks]

Originally Posted by wrwakefield

Hi Nicks,

You are right to do this kind of work yourself- especially if you are going to be caring for the boat on an ongoing basis.

I've been doing so for decades on several different vessels over time, and still learn tricks and techniques from the quality books available.

In your case, if you don't already have a copy (and it doesn't sound like you do) I suspect you would benefit from consulting Nigel Caulder's Boat Owners Mechanical and Electrical Manual [among ay other worthy publications...]

Let me know if you disagree once you peruse a copy...

Have fun with your projects!

I am absolutely going to take of it and everything that comes with it. Since it's a small boat most of the stuff will also be manageable by myself.

I'm work as an IT developer so I guess it's natural that I want to know how and why stuff works

The book you linked seems great, I've already ordered a bunch of other books as well to get some knowledge! Thanks for the tip

[kjdavie01]

My two cents - not a good idea to use the aircraft style breakers as switches - that's not what they are made for. Aircraft trouble-shooting checklists often include pulling and tie-wrapping the breaker on the troublesome circuit so that it cannot be accidentally energized - that's why you can pull them. They are not designed to be used as a switch, and will fail sooner-rather then later-if used this way.


"or if you really want to get fancy, you could go with the round aircraft style breakers that also act as switches:


They're top quality, sealed, and if you shop around, can be found fairly low priced. Notice how they're using these to isolate the batteries and alternators as well.[/QUOTE]

[Nicks]

I appreciate the advice guys, but since I am only planning to run a radio and a 12v output, installing an airplane switch panel seems a bit overkill

[Terra Nova]

Originally Posted by Nicks

...This is a an electrical system, not rocket science, just needed some help with a few things that I did not know (this is all new to me).

I don't want to hire someone for it, I want to learn how this stuff works.

It is commendable that you want to learn how stuff works. And I encourage that. But your questions tell me you would still be better off hiring a pro to wire this safely.

[Nicks]

Originally Posted by Terra Nova

It is commendable that you want to learn how stuff works. And I encourage that. But your questions tell me you would still be better off hiring a pro to wire this safely.

I gotta disagree. If we were talking about an AC-installation, then yeah probably I would hire a professional. However, 12v seems pretty manageable in that sense.

As long as you know (which I have now learned) which cable sizes and types to use and which fuses that goes with which cable then it's pretty much like assembling a PC on your own.

So if I want to hook up a 40watt light, I first need to figure how many meters I need to run the wire. Then I look in a chart to see the appropriate wire size.

I should use tinned wire for as this is for marine use. I need to install an on/off switch in between, add a fuse for the wire-size i picked. Then run that back to the battery and it's good to go.

The only problem was when I started I knew absolutely nothing about any of it, so needed to figure it all out first.

[Stu Jackson]

Good for you! None of us were born electrcians. Good idea to get some books, find the right tools and materials and PLAN AHEAD. Always draw a wiring diagram BEFORE you do the work, any electrical work. There are functional wiring diagrams and there are schematics. Both should agree. Here's an example of both:

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: Basic Battery Wiring Diagrams

Each should show how each wire attaches to a device, switch or bus bar. The only difference is the length shown on the diagrams, which, of course, you need to know to size the wire.

[hellosailor]

"None of us were born electrcians."
Damn right, Stu. The Union rules clearly state a mandatory four year apprenticeship, so unless you're the product of a four year long pregnancy...You still don't get that union card on birth, even if Mama was a Master Electrician.


Rules is rules!